Mixing bits of existing Celotex with new insulation

Postby Shane_II » Sun Jan 24, 2010 11:22 am

I had my walls surveyed for a fill and nothing was found in the walls already so the job was started. When the fillers arrived, they made a new hole and saw what they thought might be Celotex and stopped. On further inspection by the senior surveyor he could see tiny parts of Celotex in the wall and said that he wasn't allowed to mix insulators.

My house is cold because I only have a tiny amount of insulation in the walls and I am not allowed anymore. The Celotex was put in when the house was built 12 years ago.

Is their anyway of mixing insulators or do I just simply put a jumper on?

I guess I could put more insulation in the loft but only about half of it? Will this make much difference if I go from 4" to 12"?
Posts: 2
Joined: Sun Jan 24, 2010 10:58 am


Simply Build It

Postby Learning » Tue Feb 02, 2010 2:27 pm

Try and put as much insulation as possible in the loft, it is better to spread the insulation evenly than to have thick and thin areas, although half with 300mm is better than before. Make sure you leave the ventilation routes open at the eaves, above the walls, to reduce the chances of condensation on a colder roof structure. The insultation should also leave any cold water tanks on the warm side to reduce the chances of freezing.
Posts: 2
Joined: Tue Feb 02, 2010 2:19 pm

Postby Perry525 » Fri Feb 05, 2010 7:06 pm

I would suggest that you make a larger hole in the wall and take a look for yourself.
Knowing what you are dealing with puts you in a far better position to move forward.
If you look at the plans you will probably discover that there is a two inch thick layer of Celotex in the wall, which is good. And compares favorably with most existing homes.
You say that your home is cold?
That you are not allowed to add more insulation?
Why is that? In whose opinion? Why?
Can you explain what you mean by that?
Are you saying that your heating costs more to run than you think it should?
Are you allowing for the rather cold winter we have this year?
Is it that you turn the heating off at night or when you go out?
Do you give the heating enough time to warm the home when its turns on?
How long do you think it should take to warm your home?
What temperature is your room thermostat set at?
What temperature is your boiler set at?
How long is the heating on?
Posts: 733
Joined: Fri Jul 06, 2007 7:35 pm

Postby Shane_II » Sat Feb 06, 2010 10:50 am

The loft has got 4"-6" insulation along the side of 4" under a hard floor.

When the heating goes off in the evening and the house thermostat goes down to 13 degrees by the morning. I have left a thermometer in each of the rooms over a week and they are all generally down to 13 degrees at night as well. The thermostat is set at 18 degrees during the day but never reaches that temp. I am allowing for this very cold winter as my friends and family are having no difference in the warmth within their houses compared to mine. My parents have a 4 bed house and they hardly have the heating on. I have a 3 bed house and mine is on from 7am til 10pm.

I have had several walls surveyed by Mark Group. The surveyor didn't see it on the first inspection and it was the fitters that found it when they put their hole in to start. The senior inspector couldn't see it when he looked until he was told in which direction to look within the wall. They are not allowed to mix their cavity wall insulation with existing Celotex. When the house was built 11 years ago it should of had Celotex around the whole house, not in various places surely. I am thinking of approaching the builders of the house to see what was actually supposed to have been done, but not sure what this will achieve.

Is their another company that will dual fill a wall?
Posts: 2
Joined: Sun Jan 24, 2010 10:58 am

Postby Perry525 » Sat Feb 06, 2010 12:53 pm

Why do you have the thermostat set so low?
The problem being that the walls floors and ceilings become very cold overnight and you have to warm them and the air in the room before you will notice a difference.

To raise the temperature from 13°C to 18C is quite a task for any heating system, when the outside temperature is below zero.

We have had temperatures as low as minus 28C since the New Year, with the windows registering inside temperatures of 9°C with double glazing, and 16C with quadruple glazing, with a room temperature of 22C.

Try setting the thermostat at 17C overnight and check how long it takes to reach 18C.... if it does?

Try reading your gas meter every day at the same time to see if you are using a reasonable amount for your size of home.

Take a careful look at your home to see if there are any holes in the walls, floors and ceilings.
A small 9mm diameter hole in an exposed wall, can strip the heat from a room on a windy day.
Trickle vents over windows and air bricks can mean highly inflated heating bills and low temperatures in the home, block up all holes.

Buy an infrared temperature gun, and use it to sweep the walls, floors and ceilings to find the cold spots where the heat is escaping.
Posts: 733
Joined: Fri Jul 06, 2007 7:35 pm

Display posts from previous
Sort by
Order by


  • Related Topics